Iodide manipulation using zinc additives for efficient perovskite solar minimodules

Interstitial iodides are critical defects that limit efficiency and stability in perovskite solar cells and can form during solution, film, and device processing. Introducing a small amount of zinc trifluoromethane sulfinate/sulfonate (noted as Zn(OOSCF3)2) in perovskite solutions controls iodide-related defects in inks and films. The CF3SOO− anion suppresses molecular iodine formation by reducing I2 to I−, while Zn2+ cations precipitate excess iodide by forming Zn–amine complexes, thereby suppressing iodide interstitials in resultant films. Perovskite films with these additives show higher photoluminescence quantum efficiency and reduced deep trap density, with improved uniformity on large-area substrates via blade coating. Minimodules achieved National Renewable Energy Laboratory (NREL)-certified power conversion efficiencies of 19.60% (84 cm2 aperture area reported as 79.67 cm2 measured) and 19.21% (108 cm2), representing record efficiencies for these aperture sizes.